--- old/src/java.base/share/classes/java/util/UnknownFormatFlagsException.java	2019-08-27 17:29:16.502324386 -0700
+++ new/src/java.base/share/classes/java/util/UnknownFormatFlagsException.java	2019-08-27 17:29:16.314324386 -0700
@@ -36,6 +36,7 @@
  */
 public class UnknownFormatFlagsException extends IllegalFormatException {
 
+    @java.io.Serial
     private static final long serialVersionUID = 19370506L;
 
     private String flags;